Finished design of front suspension Rx7 FC to 323 sub-frame

So I threw out the original design as I didn't like a few aspects of it, mainly being that it was overly complicated, not as flexible with the position of the steering rack to the Lower Control Arms(LCA) and not as strong. To address some of these design flaws i re-designed it around some 25X50X2.5 rectangular stock I had in the shed. I also changed the design of the brackets for the power steering rack to make them easier to position providing more flexibility during construction. I've made the height of both the the LCA's and the steering rack adjustable by 60mm in three 20mm increments.

The I've sent the parts of to the laser cutters to be cut in 3mm mild steel with all the files available here. Once they are back I'll mig weld them together as I don't posses a TIG welder at this time.

New Sub-Frame Design

Old Sub-Frame Design

I built the old design in cardboard after printing it on paper sticking it to the cardboard and cutting it out. This identified a couple of issues with the position of various holes which I corrected.

Current Status of the Mazda, old engine, gearbox and steering out.

Comments

Transmission Options

I ended up going with a 2008 RX8 S2 gearbox as it was stronger than the S1 gearbox and newer and cheaper than an RX7S5 turbo box. I considered the gearbox form an RX7 FD but they have a pull style clutch which would mean I couldn't use my existing clutch. The choice of the RX8 gearbox came down to availability, cost and the fact I could use my existing clutch. I think I'll need to change the Diff Ratio from 3.27 to 4.11 to make the gearbox more usable, below is a simulation with a 4.11 Diff and the RX8 Gear ratios shifting at 8000rpm with 15inch tyres. Some of the options Jatco 3 speed automatic box including torque converter $7,000 JK40C/CD transmission from 350/370Z Adapter kits: http://collinsadapters.com/index.php/adapter-plates/mazda-rotary-13b-20b-26b-to-nissan-6-speed-350z-370z-350zhr-370zhr-transmission-adaptation-kit.html https://www.rx7club.com/rotary-car-performance-77/jk40c-cd009-transmission-370z-13b-1090772/page9/ they all seem to need: Does Not include (but requi...

The Journey continues

"It was the best of times, it was the worst of times" C.Dickens Long time no blog post, I guess most of the time I post on Instagram and neglect to come on here. In some ways it has been a good time for the shed and in other ways not so much. After moving house and getting a bigger shed I have more space, I've managed to purchase a Mill and a band saw as well as some other tooling. I've spend a fair bit of time mucking around with the front suspension and I think I have it how I want it now. Unfortunately with four children, the property, kids sport etc there is not a lot of time to spend in the shed, mostly later in the evening once everyone is in bed. I made a bit purchase and brought an RX7 FC, S5 13B motor in unknown condition with a MicroTech LT-9c for $3,000. I've started stripping it down and will clean it up and rebuild it, with the view of running it on E85. I've reworked the design of the steering rack location to have it correctly in f...

Shortening the Diff

I have a Ford 8.8 inch diff from a EF/EB Ford Falcon with a Limited Slip Differential. I want to shorten it down to suit the 323. Due to the RX7 LCA in the front, the front tyres(205X50X15) now protrude from the front guards by 65mm. Making the overall front track width 1,675mm. With 225X50X15 tyres on the rear and the standard diff the rear is 1,610mm. Meaning that the rear track width is 32.5mm narrower on each side. To widen the rear when I shorten it, I'll make the rear axle 65mm wider than the standard rear axle. The standard 323 Diff width is 1,338mm and the Ford 8.8 is 1,547mm for a total difference of 209mm. So the Diff needs to be shortened by 209mm - 65 = 144mm or 72mm per side.

Sams Shed

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